Friction

Friction is a force that acts in a direction ___________ of movement.

• similar

• opposite

• parallel

• perpendicular

Which type of friction occurs when objects are not moving?

• static

• sliding

• kinetic

• rolling

How can friction be reduced?

• Reduce the force acting between the two surfaces.

• Reduce the roughness of the two surfaces coming in contact.

• Use wax, grease, or oil.

• All of the above are ways of reducing friction.

The amount of friction depends on the weight of the objects pressing together.

• True
• False

A hockey puck slides on ice at a constant velocity. What is the net force acting on the puck?

• Zero
• Equal to its weight
• Less than its weight but greater than zero
• Depends on the speed of the puck

Tags

NGSS.MS-PS2-2

What are the units on the coefficient of friction?

• none
• Newtons
• meters
• kilograms

What is the force of friction between a 950-N block of ice and the horizontal ground if μ = .12?  $F_f=\mu_sF_n$  

• 65 N

• 226 N

• 175 N

• 114 N

What is the coefficient of static friction if it takes 44 N of force to move an 86-N box on a horizontal surface?
 $μ_s\ =\ \frac{F_f}{F_n}$  

• 0.78

• 0.51

• 0.78 N

• 0.58 N

A box requires 40 N to start it moving on a horizontal surface when the coefficient of static friction is .54. What is the weight of the box?

 $μ_{s​}=\frac{F_f​}{F_n}​​$  

• 81 N

• 18 N

• 98 N

• 74 N

Friction is a force that acts in a direction ___________ to the surface.

• similar

• opposite

• parallel

• perpendicular